Project code



School of Civil Engineering and Surveying

Start dates

October, February and April

Application deadline

Applications accepted all year round

Applications are invited for a self-funded, 3-year full-time or 6-year part time PhD project.

The PhD will be based in the Faculty of Technology, School of Civil Engineering and Surveying, and will be supervised by Dr Keiron Roberts and Professor John Williams

The work on this project could involve:

  • Identification of the main types of waste sea shells from the seafood industry
  • Modifying the most appropriate shells through various thermal and chemical processes to create a reactive media
  • Laboratory trials of the ability of the shell media to remove phosphorous from wastewater
  • Use of analytical and visual methods to study the removal mechanisms
  • Assessment of the P enriched shells as a fertiliser for the growth of crops.

Phosphorous fertilisers are usually mined and are limited in supply. Phosphorous in wastewater effluents causes eutrophication of surface waters and is facing increasingly more stringent permits. It is also a wasteful open loop system wasting phosphorous. Conventional removal is by dosing with ferric salts which are becoming increasingly expensive and is not appropriate for small rural sites. Reactive media in filters and wetlands is an attractive passive solution, but existing media cause problems of increasing pH or leaching of metals.  

Studies, mainly using oysters in Asia, have shown that modified sea shells can take up P from effluents avoid some of the problems of existing P removal. This could form the basis of a circular economy approach where by waste shells are used to concentrate P on their surfaces and then crushed to form a fertiliser. This project will identify the best sources of shells in the UK. It will then optimise their modification through thermal (calcination) and chemical treatments. These media will be tested in the field to assess their long- term P removal performance and to understand the mechanisms involved (e.g. precipitation, adsorption etc). Finally, the materials will be assessed for their suitability as a fertiliser, combined with an engineering, environmental and economic market analysis of the suitability of the material for full scale application in wastewater treatment.

Conventional reactive media have been extensively studied in previous PhD projects at Portsmouth and also in an Ofwat innovation fund project. We therefore have experience and expertise in the experimental methods required. Our unique field station at a waste water treatment works allows us to test media using real sewage and we are well equipped with analytical kit to support the project (e.g. XRD. XRF, SEM).

Entry requirements

You'll need a good first degree from an internationally recognised university (minimum upper second class or equivalent, depending on your chosen course) or a Master’s degree in an appropriate subject. In exceptional cases, we may consider equivalent professional experience and/or qualifications. English language proficiency at a minimum of IELTS band 6.5 with no component score below 6.0.

Knowledge of environmental engineering or science.

How to apply

We encourage you to contact Dr Keiron Roberts ( to discuss your interest before you apply, quoting the project code.

When you are ready to apply, please follow the 'Apply now' link on the Civil Engineering PhD subject area page and select the link for the relevant intake. Make sure you submit a personal statement, proof of your degrees and grades, details of two referees, proof of your English language proficiency and an up-to-date CV. Our ‘How to Apply’ page offers further guidance on the PhD application process. 

When applying please quote project code: SCES7630423.